This invention relates to mixing and aeration impellers, flotation assemblies in which the impellers are utilized, flotation cells in which the flotation assemblies are deployed, and flotation devices comprising the impeller, flotation assembly and flotation cell operating in combination. Specifically this invention provides a method and apparatus for mixing and aerating slurries processed in flotation devices to recover mineral values therefrom.
The mineral processing industry has found it necessary to treat ever-increasing amounts of lower and lower grade ores. This has required the use of correspondingly increasingly large processing equipment, including flotation devices. Consequentially, there is a need for flotation devices that can more efficiently separate valued minerals, such as copper, from a ground ore.
Flotation devices typically operate as follows: a slurry is prepared from a ground mixture of ore and a liquid which is typically water with selected conditioning, collecting and frothing agents. The slurry is fed into a flotation device comprised of one or more flotation cells. In the flotation cells, means, for instance mechanical means such as impellers, are typically employed to aerate and physically mix the slurry. Aeration and mixing are desired to simultaneously produce bubbles in the slurry and to bring ore particles in contact with the bubbles. As is known, ore particles having desired mineral values tend to be carried to the surface of the slurry to form a froth which may be regarded as a concentrate of the desired mineral value to be recovered. Some particles, which tend to be the heavier particles which are frequently rich in the desired mineral value, tend to settle to the bottom of the flotation cell. In order to improve the efficiency of the flotation machine process it is desirable to thoroughly mix and suspend as many particles as possible in the slurry without overmixing or agitating which could reduce the opportunity for bubbles to transport desired particles to the surface.